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binocular/ glass question |
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walleyesfairlanes
Optics GrassHopper Joined: October/16/2009 Status: Offline Points: 1 |
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Posted: October/16/2009 at 09:57 |
From the research I have done and different selected glass that I have purchased, there seems to be a very real relationship between the square value of Magnification and the size of the objective lens. (If you have a 7x then lens should be 49mm). Can anyone explain to me WHY this seems true? I have a Lueopoled FIII 6x 40mm that I can see through in darn near black night. I have read in several places that this is darn near a perfect match for optimum low light performance. I was just hoping someone on this sight could explain this to me? I am looking at purchasing a set of mid level binoculars and was just looking for the best set in low light conditions.
Thank you for your help. |
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FrankD
Optics Journeyman Joined: November/11/2005 Location: United States Status: Offline Points: 686 |
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walleyesfairlanes,
There is a bit of animated debate over what is considered the "perfect glass" for low light performance. Many folks promote higher magnification (all else being equal) because you can see greater detail on any given object (a 10x42 or 10x50 for example). Other support the "brighter image" perspective in that they prefer binoculars that might have lower magnification (6-8x) but larger objectives.....40-56 mm. In that case the overall image seems brighter because more light gets to your eyes (larger exit pupil). That is up for debate though as once you hit a certain age your pupils do not get large enough to take advantage of the larger exit pupil of the binocular.
I have not heard of your suggestion with the square of the magnification. It does make some sense but if you want 10x binoculars then you need a 100 mm objective.
I don't think they make those.
;)
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Frank
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Bird Watcher
Optics Master Joined: August/30/2006 Status: Offline Points: 1523 |
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That statement does not hold true across-the-board.
I am 62 and my eye pupils dilate to 6mm, in low light, in the eye doctors office, w/o using any kind of eye drops.
The only way for a person to know, for sure, is to have the eye pupils measured during an eye exam.
Stan
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FrankD
Optics Journeyman Joined: November/11/2005 Location: United States Status: Offline Points: 686 |
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Ok, I recant my earlier comments. You are a spry ol' man.....
Let me restate what I said earlier. For many individuals the size of their pupils isn't quite as large when they get past a certain age. Many individuals though can still utilize larger exit pupils......
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Frank
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